Coupling and method of making the same



May 22, m3. N 1,456,178

I W. P. CROCKETT COUPLING AND METHOD OF MAKING THE} SAME Filed Jan. 10, 1921' I in -fzveziZZr jy wmm ww I Patented ay 22, 1923.

E' r yr WILLIAM P. GROCKETT, OF CHICAGO, ILLINOIS.

COUPLING AND METHOD OF MAKING THE SAME.

Application filed January 10, 1921. Serial No. 436,055.

To all whom it may concern;

Be it known that I, IVILLIAM P. Cnoonnrr, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Couplings and Methods of Making the Same, of which the following is a specification.

Split-clamp couplings for securing insulated electrical conductors to outlet boxes are commonly made in the form of single-piece malleable castings each providing at its outer end a split clamp, at its middle an outwardly-extending annular collar, and at its inner end an' externally-threaded stem on which a nut may be screwed so as to clamp the margins of the outlet-box orifice between the collar and the nut, and in such stem the wire-receptive passage is reduced near its mouth or inner end by an internal flange or lipso as to form an abutment against which the end of the conductor-insulation may be positioned. Such couplings are complicated enough to be hard to cast for accurate, uniform production, and the market-products are far from satisfactory.

One object of the present invention is to provide a coupling that may have clamp. collar, stem and lip corresponding with those above described, but made of sheet-metal stampings and having advantages in cheapncss. manufacturing facility, uniformity of product, and otherwise, over the cast couplings. And a further object of my invention is to provide an advantageous method of making such sheet metal couplings.

In the drawings wherein I have illustrated a single embodiment of my invention,

in use and in course of manufacture, Fig. 1

is a perspective View showing the completed couphngm relation to an electrlcal conductor and an outlet box; Fig. 2 is a vertical secears 1212 perforated as at 1313 and having slits 14-44, all as shown in Fig. 3, these slits partly separating the integrally-connected stem-blank portion 15 and clampblank portion'16. I first form such blank to shape its inner end portion 15 into a cylindrical stem-part 15 and its outer portion 16 into a parti-cylindrical clamp head 16 from the somewhat separated contiguous edges of which there project, nearly radially or substantially in parallelism, the ears 12 of the clamp. The slits 14: of course give the portions of the clamp head contiguous to the ears a capacity to be sprung i or out, independently of the cylinder-for ed stem portion. In manufacture. it is generally desirable first to perforate the holes 13 in the sheet metal and to use them as gauge-point-receptive openings in the simple operation of stamping out the blanks in the form as shown in Fig. 3.

Where one ear of each clamp isto be tapped, for reception, of a clamp screw, 17, a stack of the blanks may be tapped in a single operation for economy.

To afford a, collar or flange between the clamp end and the stem end.of the coupling I employ a separate ring, preferably. reccomplete tangular in cross section, that may be cut from a tube or stamped out of sheet metal.

This ring is tightly fitted, preferably with a drive fit, over what I may call the root portion or centerward end of the cylinderformed stem 15", so that it almost, or quite, abuts against the inner edges of the cars 12. It may thus be positioned with ample rigidity to act as a permanent, immovable collar. 'Additionally, this solid ring provision materially strengthens the device and locks the seam-edges of the stem against spreading or opening from their tightly-a-butted relation.

The mouth or cylinder isnswaged (as by a simple press-operation) to form the inwardly extending lip op flange 19, and then the stem is externally threaded as at 20, to

complete the stem-part 15.

The order of operations stated is not' beyond variation, but is highly desirable, since the placement of the ring before the swaging operation occurs gives the cylinderformed stem a desirable accuracy of diameter and requisite stiffness to stand the rib-forming and the threading of the stem after the swaging operation avoids likelihood of malformation of threads.

The coupling element as shown in Fig. 4 is a merchantable article of manufacture, but when sold usually is supplemented by a screw 17 to complete the clamp and a nut 21 corresponding with the stem threading.

Its use in conjunction with an insulated conductor 23 and an outlet box 24 or other conductor-receiving fitting is for the same purpose as the cast couplings heretofore employed and needs no specific description. The advantageous freedom from the fins,

. bumps, blow-holes, and other irregularities that make defective so many cast couplings, and the uniformity of the product in general make advantageous the use of the device because it increases the quickness of application and thus saves labor expense. In manufacture the cheapness of the article is noteworthy and is furthered by the minimization of defectives spoiled in the making.

While I have herein described in detail a specific embodiment of my invention it will be understood that changes in detail may be made without departure from the spirit of my invention within the scope of the appended claims.

I claim:

1. A- coupling of the character described comprising an integral sheet metal element shaped to form a lengthwise-seamed cylindrical stem-portion and a lengthwise-split clam portion, and a ring element surrounding t e root of the stem portion holding the stem-seam closed and constituting a flange or collar between the stem portion and the clamp portion.

2. A coupling of the character described comprising an integral sheet metal element shaped to form a lengthwise-seamed cylindrical stem-portion and a lengthwise-split clamp portion, having projecting, nearlyparallel screw-receptive ears, and a ring element surrounding the root of the stem portion holding the stem-seam closed and constituting a flange or collar between the stem portion and the clamp portion.

3. A coupling of the character described comprising an integral sheet metal element shaped to form a lengthwise-seamed cylindrical stem-portion externally threaded and having an internal mouth-rib and a lengthwise-split clamp portion, and a ring element surrounding the root of the stem portion holding the stem-seam closed and constituting a flange or collar between the stem portion and the clamp portion.

4. A coupling of the character described comprising an integral sheet metal element shaped to form a lengthwise-seamed cylindri'cal stem-portion anl a lengthwise-split clamp portion, having projecting, nearlyparallel screw-receptive ears, and a ring element surrounding and making permanently set frictional engagement with the root of the stem portion holding the stem-seam closed and constituting a flange or collar between the stem portion and the clamp portion.

5. The method of making a coupling of the character described, which consists in forming a suitable sheet-metal blank of two integral portions into lengthwise-seamed cylindrical stem form as to one portion and lengthwise split-clamp form as to the other portion, investing the root of the cylindrical stem portion with a permanent collar-forming ring forcing the mouth of the stem into an inwardly extending lip and externally threading the stem portion. 6. The method of making a coupling of the character described, which consists in forming a suitable sheet-metal blank of two integral portions into lengthwise-seamed cylindrical stem form as to one portion and lengthwise split-clamp form as to the other portion, investing the root of the cylindrical stem portion with a permanent collar-forming ring and externally threading the stem portion.

Subscribed and sworn to at Chicago, Illinois, this 10th day of December, 1920.

WILLIAM P. CROCKETT. 

